The objective of the Phase I studies is to provide the parameters and characteristics of drug toxicity, the maximally tolerated dose, the recommended dose and the basic pharmacokinetics of these agents. Drugs tested will be limited to oral synthetic retinoids. Vitamin A and its synthetic analogs, collectively known as retinoids, have been actively studied in relation to their requirements in normal physiology and health as well as for their potential in prevention of human disease, notably cancer. In this regard, it has been established that: 1) Supplementation with retinoids can reverse tissue metaplasia and neoplasia in various laboratory models, restoring normal cell differentiation; and 2) Retinoids administered to animals can prevent chemical and viral induced carcinogenesis. They have been repeatedly shown to delay the appearance, retard the growth, cause the regression and prevent metastases of selected tumors. In addition, several epidemiological studies have shown an association of low levels of vitamin A with increased risk of cancer. Based on this evidence and case reports demonstrating the successful chemoprevention of basal cell carcinoma with large doses of the retinoid isotretinoin, Phase I clinical trials using other new oral synthetic retinoids are proposed. Three new oral synthetic retinoids will be evaluated over the next one-year period with therapeutic intent for the dermatologic conditions of acne, psoriasis, disorders of keratinization (ichthyoses and Darier's Disease), basal cell carcinoma and other related dermatologic disorders. The studies will be designed to allow dosage escalation from a presumed non-toxic dose to a dose showing either substantive efficacy or toxicity. When moderate toxicity is reached, modification to lower doses will be made and patients examined monthly for chronic toxicity. Maximum duration of continuous treatment will be six months. The specific objective is to establish safe and tolerated dose for conducting Phase II-III chemoprevention trials.